Car-axle-lighting system.



J. L. WOODBRIDGE. CAR AXLE LIGHTING SYSTEM. APPLICATION FILED JAN. 10, 1908.

Patented July 15, 1913.

2 SHEETS-SHEET 1.

M e RX man mz o VafiT H M fiat Q N, .M L MO nN w/ h of the invention,

JOSEPH LESTER WOODIBRIDGE, OF PHILADELPHIA, PENNSYLVANIA.

CAR-AXLE-LIGHTING SYSTEM.

Specification of Letters Patent.

Patented July 15, 1913.

Application filed January 10, 1908. Serial No. 410,259.

To all whom it may concern:

Be it known that I, J OSEPH L. Woon- BRIDGE, a citizen of the United States, and resident of Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented certain new and useful Improvements in Car-Axle-Lighting Systems, of which the following is a specification.

My invention relates to systems in which a generator driven at variable speed is used for supplying current'to a constant potential circuit, as in the case of a generator for train lighting driven from the axle of the moving car, or a generator driven by a windmill at variable speed.

The principal object of'my invention is to provide simple and reliable means for maintaining a constant potential at the generator terminals with widely varying speed changes.

Other objects as well as the general nature and scope of my invention will be more clearly seen from the following description taken in connection with the accompanying drawings, in which p Figure 1, represents an axle lighting system in a simplified form embodying features and Fig. 2, is a modification of this s stem.

In Fig. 1, is a direct current generator supplying current to the translating devices L and driven at a variable speed by means of a belt M running one pulley mounted on the car axle. 'On the same shaft as the generator armature, is mounted an exciter E. This exciter consistsof a frame or core of magnetic material 8, on which is a" winding 9, connected to a commutator 10, in the usual manner, only a few of the connections being shown on the drawings for the sake of clearness. To avoid confusion, only a few of the connections from the winding to the commutator are shown. Two pair of brushes 45. and 67 bear upon this commutator at points displaced at. an angle of 90. One pair of brushes 4.5 is connected to a source of constant potential, .here shown as a storage battery B. The other air 67, is connected to the field windings 4 and S of the generator G.

The operation of this apparatus is then as follows: Assume first that the generator G and the exciter E, are driven at a certain fixed speed; the battery will tendto send current through the armature winding 9 between the brushes 45. This current would become excessive were it not for the counter electro-motive-force developed in this armature by reason oi its rotation in the field produced by the current output from the brushes 67 as explained below. Assume a small amount of current flowing in the armature winding 9 between the brushes 45. This current will produce a field whose axis will be in line with the brushes 4-5. This field will produce an electro-motive force across the brushes 6 7 and this electro motive force will send current through the field windings S and S of the generator G. The efi'ect of this latter current, however, on the exciter E will be to' produce a second field whose axis will be in line with the brushes 67, and this second field will produce a counter electro-motiveforce between the brushes 45 suflicient to prevent any further increase of current from the battery. It will be seen that for any given speed the flow of current from the brushes 6--7 through the field windings S? and S will depend upon the voltage of the the field necessary to develop the counter .electro-motive-force required to nearly balance that of the battery. If, however, the speed should increase, a weaker field, and therefore a smaller amount of current from the brushes 67 will be required to produce the same counter electro-motive-force. It will be seen, therefore, that as the speed of the generator and exciter varies, the current in the field windings S and S will vary in the opposite direction, thus maintaining constant voltage onthe generator G, regardless of changes of speed. It will also be noted that i'fthe direction .of rotation reverses, the current in the field-windings S and S will also reverse, so that the generaf tor will maintain the same polarity.

The system as shown in Fig. 1, is open to two objections; First, if the speed becomes very low the amount of current flowing from the battery into the exciter and the amount of current flowing from the exciter through the field windings S and S will both become abnormally great. Second, the battery B, is always discharging and means must therefore be provided for charging this battery when not in service. In the system shown in Fig. 2, these two objections are eliminated, and certain-other modifications are introduced. The generator G is shown as a three pole machine provided with three connected by contacts on the switch S with brush 1..

The enci-ter E operates as described in connection with Fig. 1, the brushes l5 being connected across the battery terminals, while the brushes -67, supply current to the field windings S S and S. An automatic switch S, is shown, designed to disconnect the exciter from the battery automatically when the flow of current from the battery to the exciter is abnormally great and :at the same time to disconnect the battery from the generator G and connect it directly to the lamp circuit. This switch S, is operated by an electrom'agnet opposing an adjustable spring K. In the position shown, the pull of the spring K, preponderates and brush 1 of the generator is connected to the negative terminal of the battery and to the lamp circuit by means of the contact points Q and R, which make contact with a conducting plate J, on the switch S.- Brush 4, of the enciter E is permanently connected to conductor 12, which is connected to the negative terminal of the battery, while brush 5, of the exciter E, is connected to the positive terminal of the battery by means of contact N, which makes contact with the conducting plate 1, on the switch S, the plate 1,..being connected to the positive battery as shown. r in the "circuit between the contact N and the brush 5, is a coil 0, wound on the electroniagnet A. A second coil C is also wound on the electronnagnet in the same direction as the coil C having its terminals connected to the circuit on opposite sides of the contact N, so that when this contact is broken, current will flow through the coil C A resistance :F, is shown in series with the coil which may be used to adjust its effect. The coils C and C are so designed that when the current flowing from the battery through the eXci-ter by way of the binushes 4-5 exceeds a certain predetermined amount,- the force of the spring K, will be overcome by the pull of the electromagnet A and the switch S will'be thrown oven, the coil G being then sufficient to hold it in the new position. This will break the contacts at the points Q and R, disconnecting the -generator from the battery, and will also break the contact at N, disconnecting the battery trom the exciter, except for the small amount of current which will flow through the coil C this being a coil of many turns of fine wire.

In the second position of the switch S, the contact plate 1, makes contact with the points 0 and P By means of the contact with the point 0, the battery terminal is connected directly to the lamp circuit, .and by means of the contact P, a third coil D, on the electr0magnet A, is connected at one terminal throughthe contact plate I and point 0, with the brush 2, of the generator G while the other terminal of thecoil D, is permanently connected to brush 1, of the generator G This coil is wound differentially with respect to the coils C and "C and is so designed that when the voltage of the. generator G increases to a certain point the coil D: will sutlic-iently neutralize the effect of the coil C to permit the spring K to prcponderate and pull the switch back to its original position. The voltage between the brushes 1 and 2 of the generator G necessary to eXcite the coil D in this way will be produced by the small current flowing through the excite-r by way of the resistance F and the coil and the resultant current flowing from the brushes 6-''(' through the field windings S S and S the result being that when the generator G has reached a certain predetermined speed,

the switch S will be thrown into the position shown in Fig. 2, automatically.

When the apparatus is connected as shown in 2, it will be seen that the battery B is charging and at the same time maintaining the voltage across "the brushes 4r5 of the enciter E. Without some controlling apparatus this arrangement would be unstable since increase in the battery voltage would cause a corresponding increase in the generator voltage and there would be nothing to prevent a wide variation of generator voltage, since the voltage of battery and generator would go up and clown together. In order to maintain a constant battery voltage regardless of changes in the generator voltage the regulator U is shown interposed in the circuit between the brush 3, of the generator and the battery. This regulator consists of a pile of carbon disks V, which are connected in series with the conductor 11, These disks are subjected to pressure by means of a lever pivoted at X. The pressure is produced by an adjustable spring Z, whose tension is opposed by a solenoid at the opposite end of the lever excited by two coils T and T The coil '1, is connected across the terminals of the battery, while the coil 'T is connected between the brushes 1 and 3, of the generator. These two coils are wound in the same direction and cooperate to relieve the pressure on the carbon pile V. As is well known, the resistance of the carbon pile will increase when the pressure is released. If, therefiore, the voltage OIE the battery should slightly increase the pull produced by the coil T will preciable increase in the charging current,

and the battery voltage will not increase.

What I claim is: 1. A dynamo and its excitermechanically I connected, two sets of electricall displaced brushes for the e-xciter, 'whereo --one set'is connectedto a source of constant potential while the other is connected to the field windings of the dynamo.

2. A dynamo, a variable speed driving source for said" dynamo, an exciter, means for driving the exciter at'a speed proportional to that of the dynamo, two sets of electrically displaced brushes for the exciter, whereof one set is connected to a source of constant potential while the other is connected to the field windings of thedynamo.

3. In combination a dynamo having appropriate field windings, a consumption circuit, a commutator, two sets of brushes bearing upon said commutator, a circuit including the field windings of the dynamo connecting the opposite brushes of one set, another circuit including a storage battery connecting the opposite brushes of the other set, means including a magnetic circuit and coils thereon connected to the commutator for producing between the' o posite brushes of each set an electro-motiveorce controlled by the current in the circuit connecting the other set, means for producing relativerotation of brushes and commutator proportional to the speed of the dynamo, and means for inter osing resistance between the battery and t e brushes and connecting the battery to the consumption circuit when the speed of .the generator falls below a certain limit.

4. In combination a dynamo having appropriate field windings, a consumption circuit, a commutator, two sets of brushes bearing upon said commutator, a circuit including the field windings of the dynamo connecting the opposite brushes'of one set, another circuit including a storage battery connecting the o posite brushes of the other set, means inclu ing a magnetic circuit and coils thereon connected to the commutator for producing between the opposite brushes of each set an electro-Inotive-force controlled by the current in the circuit connecting the other set, means for producing relative rotation of brushes and commutator proportional to the speed of thedynamo, connections for. charging the battery from the dynamo including a variableresistance, an electro-responsive device for controlling said resistance, and means for disconnecting the battery from the generator and connecting it to the consumption circuit when the speed of the generator falls below a certain point. 5. In combination a consumption circuit,

' a storage battery, generating apparatus having appropriate field windings and adapted to develop two different electro-motiveforces whereof'one is suitable for the con sumption circuit and the other for charging the battery, appropriate connections from the generating apparatus to the consumption circuit and the battery, a variable speed source, of power for driving the generating apparatus, and means responsive to changes in the speed of the driving source and controlled by the voltage at the battery terminals for varying the current in the field windings.

6. In combination a consumptioncircuit, a storage battery, generating apparatus having appropriate field windings and adapted to develop two difierent electro-motiveforces, whereof one is suitable for the consumption circuit and the other for charging the battery, appropriate connections from the generating apparatus to the consumption circuit and the battery, a variable speed source of power for driving the generating apparatus, means responsive to changes in the speed of the driving source and controlled by the voltage at the battery termi- I nals for varying the current in the field windings and means responsive to changes of battery voltage for controlling the battery charging current.

7. In combination a consumption circuit, a storage battery, generating apparatus having appropriate field windings and adapted to develop two different electro-motiveforces, whereof one is suitable'for the con-' sumption circuit and the otherfor charging the battery, appropriatefconnections from the generating apparatus to the consumption circuit and the battery, a variable speed source of power for driving the generating apparatus, means responsive to changes in the speed of the driving source and con-. trolled by the volta e at the battery terminals for varying tEe current in the field windings, and means responsive to changes of voltage of the battery and the generating apparatus for controlling the battery charging current.

'8. In combinationaconsumption circuit, a storage battery, generating apparatus having appropriate field windings and adapted to develop two diiferent 'electro-motiveforces, whereof one is'vsuitable for the consumptioncircuit and the other for charging the battery, appropriate connections from tion circuit and the battery, a variable speed source of power for driving the generating apparatus, means responsive to changes in the speed of the driving source and controlled by the voltage at the battery termi- Ila-ls for varying the current in the field windings, and means responsive to changes of voltage of the generating apparatus for controlling the battery charging current.

9. In an electrical system a variable speed dynamo having appropriate field windings,

a storage battery, means responsive to changes in the dynamo speed and controlled by the voltage at the battery terminals for varying the current in the field windings and connections for charging the battery.

from the dynamo, in combination with means responsive to changes in the voltage of the dynamo for controlling the charging current to maintain the battery voltage substantially constant.

10. In combination a varlable speed dynamo having appropriate'field windings, an eXciter for said dynamo comprising an armature and its commutator and two pair of relatively displaced brushes bearing on said commutator, a circuit including a storage battery connecting the brushes of one pair, connections from the other pair to the field windings of the dynamo, means for driving the exciter at speeds proportional to and varying with the dynamo speed, and

connections from the dynamo for charging the battery including a regulator adaptedto control the charging current to maintain substantially constant voltage at the battery terminals.

In testimony whereof I have hereunto signed my name.

i JOSEPH LESTER WOODBRIDGE. In the presence of,

WM. J. JACKSON, FRANK E. FRENCH. 

